The present invention relates generally to ice scrapers and more particularly to bladed, anti-scratch, multistate water precipitation removing tools for delicate surfaces.
Removal of ice, frost and slush from airplane wing surfaces and from airplane windscreens is a well-known flight safety necessity. More serious than the additional weight burden is the destruction of the wing lift due to the disruption of laminar flow caused by ice or frost. A mere 1/16" of rough, heavy frost can disastrously reduce wing lift. However, this same 1/16" of frost, once polished, has little effect on lift. Two options then exist: (1) removing all precipitation from the wing surface, or (2) polishing smooth any frost, crusty snow or rough ice. Large, commercial airline companies generally employ chemical deicers. That is, alcohols or other ice removing chemicals are sprayed on the wing surfaces and windscreens. However, these fluids are too heavy to carry on board an airplane in quantities necessary for effective deicing of large wings and are also dangerous to transport. Unfortunately, small and/or remote airfields do not ordinarily have the required deicing agents. Corporate and private aircraft owners must therefore utilize relatively crude mechanical means for snow and ice removal. Water and slush must also be removed by any means available because they will form frost and rough ice as the airplane taxis or takes off.
No tools exist in the aviation market for achieving the desired precipitation removal. Ordinary plastic ice scrapers prevalent in the automobile industry are useless since they can easily scratch airfoil surfaces and plastic windscreens. Household brushes and brooms, rags, sheets, ropes, and burlap bags are most commonly used by pilots to remove snow and to polish frost. Alcohol or hot air from an engine heater may be used on ice or the pilot may resort to solar melting or a heated hangar, if available. Water and slush are most usually removed using rags since industrial floor squeegees have metal frames that can gouge aluminum wings. They also incorporate rubber blades that become brittle and ineffective in cold weather, leaving streaks and blemishes on painted surfaces.
Wing surfaces are constructed of lightweight, easily damaged material. Dope and fabric have been used in the past. More recently, painted aluminum alloys, fiberglass and composite plastics are being used. However, all of these materials are easily gouged and permanently damaged by hard plastics resulting in an unairworthy airfoil. Moreover, sharp, hard plastic scrapers cannot ride over the rivets emplaced on the wing in the construction procedure; hard plastic blades then, generally either damage the rivets of break.
The difficulty in using softer plastics, which theoretically would approach the desired flexibility and hardness at lower temperatures, is the large range of temperatures at which further wing deicing is necessary. That is, pilots typically face ground temperatures of approximately 0 to -40 C. during and after a winter storm. Clearly what is needed is a material which is suitable for scraping, polishing and squeegeeing a wing surface or windscreen without damaging it and one which maintains its properties of flexibility and hardness relatively constant throughout this broad temperature range.
A series of commercially available, easily moldable, elastomers has been developed by E. I. duPont de Nemours and Co. under the Tradename, `Hytrel`, which combines the characteristics of rubbers and plastics. Resistance to stiffening at low temperatures is quite remarkable. Fortuitously, these synthetics include flexibilities appropriate to the requirements of the instant invention. Compositions soft enough to squeegee water from surfaces are included at one end of the list of available materials, while those hard enough to scrape off light ice are covered by the other end of the product list. Intermediate flexibility materials suitable for polishing frost are also available. Three relevant bulletins from E. I. duPont de Nemours and Co. describe these products: HYT-501A, "Mechanical Properties of `Hytrel`"; HYT-001A, "Types, Properties and Uses of `Hytrel`;" and E-26276, "Engineering Guide to the duPont Elastomers", the disclosures of which are hereby incorporated by reference. The third of these publications lists 23 uses for these materials, none of which teaches my invention. These bulletins list the properties of `Hytrel`, but they should be regarded as properties which define the materials from which my tool can be fabricated should other materials possessing similar properties become available. The squeegee blades in two embodiments of my invention are fabricated from silicone rubber.
The tool of the instant invention is fabricated from these duPont Elastomers which allows it to be used to satisfy the need in the aircraft industry for a nondestructive, multistate water precipitation remover from wing surfaces and windscreens. Moreover, the nondestructive scraping action of my tool will permit paint removal from wing surfaces when it is used with appropriate solvents. The third of the bulletins cited hereinabove describes the insensitivity of `Hytrel` to a wide variety of oils, fuels, solvents, and chemicals, thereby allowing its use as a paint scraper in the presence of these chemicals. Finally, my tool can be used for cleaning any delicate surface such as motorcycle windscreens, for example.